Search code examples
c#drag-and-dropgtkgtk#gtktreeview

In Gtk, when using Drag and Drop in a TreeView, how do I keep from dropping between rows?

I'm testing a window that looks something like this:

alt text

Dragging a Tag to a Card links the Tag to the Card. So does dragging a Card to a Tag.

It's meaningless to drop a tag between two cards, or a card between two tags. I can ignore these outcomes in the Handle...DataReceived function like this:

if (dropPos != TreeViewDropPosition.IntoOrAfter &&
    dropPos != TreeViewDropPosition.IntoOrBefore)
    return;

However, when dragging, the user still sees the option to insert:

alt text

How do I prevent this from happening?

Solution

  • You need to connect to the drag-motion signal and change the default behaviour so it never indicates a before/after drop:

    def _drag_motion(self, widget, context, x, y, etime):
    drag_info = widget.get_dest_row_at_pos(x, y)
    if not drag_info:
        return False
    path, pos = drag_info
    if pos == gtk.TREE_VIEW_DROP_BEFORE:
        widget.set_drag_dest_row(path, gtk.TREE_VIEW_DROP_INTO_OR_BEFORE)
    elif pos == gtk.TREE_VIEW_DROP_AFTER:
        widget.set_drag_dest_row(path, gtk.TREE_VIEW_DROP_INTO_OR_AFTER)
    context.drag_status(context.suggested_action, etime)
    return True